1. Field of the Invention
The present invention relates to a modified regenerated cellulose fiber containing a grounder of naphthol dye, which can be dyed by treating with a developer of naphthol dye when it is used alone or as mixed yarn or union knitted/woven fabric, and enables dyeing melange yarn or union knitted/woven fabric in different colors, and also relates to dyed fiber products thereof.
2. Description of Related Art
It is well known that a dyeing method for cellulose-based fiber using a naphthol dye is the one in which two kinds of dye intermediates composed of a grounder and a developer are absorbed in cellulose-based fiber in solubilized state separately followed by reacting to form water insoluble azo dyes on cellulose-based fiber, and that various hues can be obtained depending on combinations of a grounder (naphthol ASs) and a developer (bases, salts).
Naphthol dye has features that it can provide a vivid hue mainly in reddish color and a deep color with a high fastness. While reactive dyes are mainly used for cellulose-based fiber, naphthol dyes are also used especially for a deep color with reddish hue. However, a dyeing process using naphthol dye is much more complicated compared with that using a reactive dye or the like. In the dyeing process using a naphthol dye, in order to dissolve a grounder (naphthol ASs) which is insoluble in water, it is necessary to make the grounder mud-like by adding a surfactant such as Turkey red oil or a dissolving agent such as ethanol, which is then dissolved carefully in large amount of hot aqueous solution of sodium hydroxide. Since this process requires great skills in using alkaline solution and controlling pH and also has diversified steps depending on which of bases or salts are selected as a developer to be used in the subsequent step, it is difficult to secure skilled dyeing workers. Thus, an improvement of this process has been required.
Spinning of a spinning solution mixed with a solid substance such as titanium oxide has been conventionally carried out. However, in a case of spinning solution containing a liquid substance, the liquid substance is thought to flow out into spinning bath. The present inventor noticed that a solution of grounder of naphthol dye can be added and mixed into a spinning solution because a spinning solution in viscose process or cuprammonium process is alkaline, and that flowing out of a grounder into spinning bath is little, and thus completed the present invention.
Objects of the present invention is to simplify the complicated dyeing process using a naphthol dye, and also to provide a modified regenerated cellulose fiber which enables dyeing melange yarn or union knitted/woven fabric in different colors with a naphthol dye even in piece-dyeing by combining a modified regenerated cellulose fiber of the present invention with other fibers by means of mixed spinning or union knitting/weaving, as well as dyed fiber products thereof.
The present inventors earnestly studied to solve the above-described problems and obtained a modified regenerated cellulose fiber which contains 0.5-3.0% by weight based on the regenerated cellulose fiber of a grounder of naphthol dye selected from the group having a medium to high level of affinity to the regenerated cellulose fiber in a matrix consisting of the regenerated cellulose fiber. Since the modified regenerated cellulose fiber of the present invention can be dyed only with a developer, the conventional dyeing process using a naphthol dye can be remarkably simplified. At the same time, as this method gives no or little staining to other fibers, it becomes possible to dye a melange yarn or an union knitted/woven fabric in different colors by piece dyeing using a naphthol dye, by combining the modified regenerated cellulose fiber and other fibers by means of mixed spinning or union knitting/weaving, and obtain the variety of fiber products.